Vehicular traffic on roadways continues to increase as populations increase and become more concentrated in certain areas, particularly urban locations. Many urban jurisdictions have constructed special lanes or implemented methods to reduce vehicle traffic and congestion. Among these, high occupancy vehicle (HOV) lanes encourage higher occupancy within vehicles, thereby decreasing the number of vehicles on roads. HOV lanes traditionally have permitted access to segregated and less populated lanes by vehicles having a driver and at least one other passenger. Other methods for managing vehicular traffic include toll roads and car pool tax credits.
While extra-vehicular cameras have been implemented to assess tolls to vehicles on toll roads by automatically recognizing a license plate in a photograph of a vehicle as it passes a toll station, enforcement of occupancy requirements in HOV lanes has remained primarily a manual process performed by state and local law enforcement agencies. Unlike vehicle-identification systems that track owner information based on a vehicle's license plate, extra-vehicular camera-based systems are not able to easily determine the number of passengers in a vehicle due to multiple factors including glare and the inability to view some areas within the vehicle.